Hollow fibre restraining system

ABSTRACT

A restraining system for hollow fibres is provided. The restraining system includes a plurality of longitudinally extending elements spaced from one another and supported by a number of discrete spacer elements, each spacer element extending generally transverse of said longitudinal elements, such that in combination with said longitudinal elements they define a cage-like structure.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/894,191, filed Jul. 19, 2004, which is a continuation of UnitedStates Application No. 10/268,600, filed Oct. 9, 2002, now U.S. Pat. No.6,783,008, which is a continuation, under 35 U.S.C. § 120, ofInternational Patent Application No. PCT/AU01/00387, filed on Apr. 6,2001, under the Patent Cooperation Treaty (PCT), which was published bythe International Bureau in English on Oct. 18, 2001, which designatesthe United States, and which claims the benefit of AustralianProvisional Patent Application No. PQ 6801, filed Apr. 10, 2000.

FIELD OF THE INVENTION

The present invention relates to a restraining system for hollow fibresused in membrane filtration systems.

BACKGROUND OF THE INVENTION

A number of different types of restraining systems usually in the formof a welded plastic mesh cage have been used in the past, however, thesesuffer from lack of rigidity when large apertures are required in themesh to allow for fluid flows and are difficult to repair should anyportion of the mesh be broken during transport, installation or use.While such known restraining systems are cheap and simple to manufacturethey suffer from a lack of robustness in many required installations.

The present invention seeks to overcome or at least ameliorate one ormore of the disadvantages of the prior art or at least provide thepublic with a useful alternative.

SUMMARY OF THE INVENTION

According to one aspect, the present invention provides a restrainingsystem for hollow fibres including a plurality of longitudinallyextending elements spaced from one another and supported by a number ofdiscrete spacer elements, each spacer element extending generallytransverse of said longitudinal elements such that in combination withsaid longitudinal elements they define a cage-like structure.

For preference, the cage-like structure is tubular. Preferably, thelongitudinal elements are rods and the spacer elements are in the formof rings. It will be appreciated that the rings may of any geometricshape and are not limited to a circular shape. Similarly, the tubularstructure and rods may be of any geometric cross sectional shape.

In one preferred form, each ring has a number of radially extendingengagement formations for releasably engaging an associated rod. Theformations may be in the form of part-circular opposed flanges spaced toprovide a socket having an interference or snap-fit with the associatedrod.

In another preferred form, each ring has a number of radially extendingcut-outs spaced around its periphery, each cut-out being sized andshaped to form an interference or snap-fit with an associated rod.Preferably, the internal surface of each ring is bevelled along eachinternal edge. For further preference, the internal surface of each ringis providing with a cushioning element. Preferably, the cushioningelement is formed of a foam material and extends past the length of eachring at both ends so as to overlap the internal edges of each ring.

The spacer elements may be formed from a number of sub-elements whichare fixed together in use.

The cut-outs or sockets are preferably equally-spaced around theperiphery of the ring.

For preference, the rods have a reduced diameter or width at thelocation where they engage with an associated spacer. Preferably, thereduced diameter is provided by a circumferential groove or slot.

The components of the system are preferably formed of generally rigidplastics material, typically nylon and acrylonitrile butadiene styrene(ABS). The components can be moulded or machined to the desiredconfiguration. The cut-outs are preferably part circular in crosssection with an opening slightly smaller than the diameter to providefor snap-fitting retention of the rods.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described, by way ofexample only, with reference to the accompanying drawings, in which:

FIG. 1 shows a perspective view of the restraining system according toone embodiment of the invention;

FIG. 2 shows a perspective view of the spacer component of therestraining system of FIG. 1;

FIG. 3 shows an enlarged exploded perspective view of the restrainingsystem of FIG. 1;

FIG. 4 shows a perspective view of the restraining system according to asecond embodiment of the invention;

FIG. 5 shows a perspective view of the snap ring component of therestraining system of FIG. 4;

FIG. 6 shows a perspective view of the adaptor ring component of therestraining system of FIG. 4;

FIG. 7 shows a perspective view of the restraining system according to athird embodiment;

FIG. 8 shows a perspective view of the snap ring component of therestraining system of FIG. 7;

FIG. 9 shows a perspective view of the adaptor ring component of therestraining system of FIG. 7;

FIG. 10 shows a perspective view of the restraining system according toa fourth embodiment;

FIG. 11 shows a perspective view of the snap ring component of therestraining system of FIG. 10;

FIG. 12 shows a perspective view of the adaptor ring component of therestraining system of FIG. 10; and

FIG. 13 shows an enlarged perspective view of the end of the restrainingsystem of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 to 3, the restraining system comprises a generallytubular cage-like structure 5 formed from a plurality of longitudinallyextending rods 6 spaced from one another and held in position by anumber of longitudinally spaced and transversely extending spacer rings7.

Each spacer ring 7 in this embodiment has a number of engagement sockets8 spaced equally around its periphery. Each socket 8 is formed bypart-circular opposed flanges 9 spaced to provide an interference orsnap-fit with the associated rod 6. The sockets 8 are slightly oversemi-circular in shape to provide retention of the rods 6.

Referring to FIGS. 4 to 13 of the drawings, each ring 7 in theseembodiments has a number of radially extending cut-outs 10 equallyspaced around its periphery, each cut-out 10 being sized and shaped toform an interference or snap-fit with an associated rod 6. The cut-outs10 in this embodiment are slightly over semi-circular in shape toprovide retention of the rods 6.

The rods 6 in this embodiment are provided with a circumferential grooveor slot 11 to provide a reduced diameter/width at the location wherethey engage with the ring 7. This serves to prevent longitudinalmovement of the rings 7 relative to the rods 6.

Each end of the tubular restraining structure 5 is provided withterminating adaptor ring 12 which, in use, mounts the structure 5 to apotting sleeve 16 or the like. The adaptor ring 12 includes a inner ring13 having a plurality of openings 14 to allow passage of fluidtherethrough and a radial extending circumferential rib 15. Rib 15 isagain provided with a corresponding number of cut-outs 16 as thoseprovided on the spacer rings 7 for engaging with the ends 17 of rods 6.

As shown in the various embodiments, the spacer rings 7 are preferablyarranged in closely-spaced pairs. Further, the number of rods and ringscan be varied according to restraint requirements. As best shown in FIG.10, the density of rod numbers can also be varied along the length ofthe tubular structure 5 where restraint requirements vary along thelength.

The restraining system is used to restrain a bundle of hollow fibremembranes employed in filtration systems. The fibre bundle extendslongitudinally within the tubular restraining system. The restrainingsystem allows fluid flow to and from the hollow fibre membranes.Typically, the fibres extend between upper and lower headers which,together with the restraining system, can be used to form a replaceablefibre bundle module. In such arrangements, the cage has the addedadvantage of protecting the fibre bundle during deployment of themodule.

It will be appreciated, that further embodiments and exemplifications ofthe invention are possible without departing from the spirit or scope ofthe invention described.

1. A filtration system, said filtration system comprising a bundle of hollow fibres and a restraining system for the hollow fibres, said restraining system comprising a plurality of longitudinally extending elements spaced from one another and supported by a plurality of discrete spacer elements, said spacer elements extending generally transverse of said longitudinally extending elements, wherein said spacer elements and said longitudinally extending elements are arranged to define a cage-like structure.
 2. A filtration system according to claim 1, wherein the cage-like structure comprises a tubular shape.
 3. A filtration system according to claim 1, wherein the longitudinally extending elements comprise rods and the spacer elements comprise rings.
 4. A filtration system according to claim 3, wherein each ring comprises a plurality of radially extending cut-outs spaced around a periphery of the ring, each cut-out configured to provide an interference-fit or snap-fit with an associated rod.
 5. A filtration system according to claim 4, wherein the cut-outs are equally-spaced around the periphery of the ring.
 6. A filtration system according to claim 3, wherein each ring comprises a cushioning element, wherein the cushioning element is situated on the internal surface of the ring.
 7. A filtration system according to claim 6, wherein the cushioning element extends past a length of the ring at both ends of the ring so as to overlap the internal edges of the ring.
 8. A filtration system according to claim 7, wherein the cushioning element comprises a foam material.
 9. A filtration system according to claim 1, wherein at least one of the longitudinally extending elements and the spacer elements comprises a generally rigid plastic material.
 10. A filtration system according to claim 9, wherein the generally rigid plastic material comprises nylon or acrylonitrile butadiene styrene.
 11. A filtration system according to claim 1, wherein at least one of the longitudinally extending elements and the spacer elements is a molded element.
 12. A filtration system according to claim 1 wherein at least one of the longitudinally extending elements and the spacer elements is a machined element.
 13. A filtration system according to claim 1, wherein the restraining system comprises a terminating adaptor ring.
 14. A filtration system according to claim 13, wherein the terminating adaptor ring is configured to mount the restraining system to a potting sleeve.
 15. A filtration system according to claim 1, wherein the spacer elements are arranged in closely-spaced pairs.
 16. A filtration system according to claim 1, wherein a number density of longitudinally extending elements varies along a length of the cage-like structure. 